D:\PerlMonks>digits1.pl
syntax error at D:\PerlMonks\digits1.pl line 5, near "chomp"
Global symbol "$inp" requires explicit package name at D:\PerlMonks\digits1.pl line 5.
Global symbol "$inp" requires explicit package name at D:\PerlMonks\digits1.pl line 6.
Global symbol "$inp" requires explicit package name at D:\PerlMonks\digits1.pl line 7.
Execution of D:\PerlMonks\digits1.pl aborted due to compilation errors.

D:\PerlMonks>

##</code><code>##

use strict;
use warnings;

print 'Please enter your card number';
chomp(my $inp = <>);
$inp =~ s/(\d{4})(\d{4})(\d{4})(\d{4})/$1 $2 $3 $4/;
print $inp,"\n";